1. Field of the Invention
This invention relates generally to articulated mechanical structures and particularly to adjustable steering columns.
2. Discussion of the Related Art
Adjustable steering columns have been in existence for some time. Early devices were based on a simple pivot joint between the upper and lower steering column housings, the steering column shafts interconnected by a universal joint. Later systems employed complex arcuate and swinging arm and adjustable links. For example, see U.S. Pat. No. 4,656,888 assigned to Kloeckner-Humboldt-Deutz AG of Germany and U.S. Pat. No. 5,259,264 assigned to AB Volvo of Sweden.
The device shown in the Volvo ""264 patent provides an adjustable steering column using a series of swinging arms. The position of the arms can be adjusted using a pair of levers pivotally joined to each other by means of a pivot pin. A control cable from an actuating pedal has a wire joined to the opposite end of one of the levers . When the pedal is depressed, the levers are moved towards each other which compress a spring package applying pressure to the joints of the arms, and permit the steering column to move.
Another form of steering column adjustment mechanism is generally illustrated in U.S. Pat. Nos. 5,131,287 and 5,606,891. Each of these devices are based upon a bracket having elongated slots in which pins translate to telescopically adjust the steering column. Tilt arrangement is provided by a second bracket within the first wherein one of the pins is also permitted to translate vertically. The ends of the pins within the slots are fixed by a friction with the brackets, the pressure exerted by a xe2x80x9cpower meansxe2x80x9d such as a hydraulic cylinder or other actuator mechanism.
The complexity of the prior systems is the primary disadvantage of those systems. Complex tooling is necessary to form the convoluted and curved arms of the Volvo ""264, which requires complicated static and dynamic analysis during the engineering stages as well as expensive tooling. With respect to the other described systems, complex locking mechanisms are required, where if pressure is lost, the position of the steering column is in jeopardy. It is a primary object of the instant invention to provide a steering column support assembly which is relatively straight forward and simple from an engineering standpoint, requires very little original tooling requirements; and is able to absorb crash energy to protect the operator.
A multi-bar linkage for a steering column, including a stationary housing, a first link interconnecting a lower end of the steering column to a distal point on the stationary housing relative to the steering column, a second link interconnecting the lower end of the steering column to a proximal point on the stationary housing relative to the steering column; and a third link interconnecting an upper end of the steering column to said proximal point on the stationary housing. A locking assembly is provided which extends through the stationary housing, an end of the second link, and an end of the third link, for fixing a relative position of the first, second, and third links relative to one another. The third link includes a longitudinal slot in an end coupled to the stationary housing, for allowing the third link to slide longitudinally relative to the stationary housing and change the steering column position relative to the stationary housing. The second link also includes a longitudinal slot in the end coupled to the stationary housing, for allowing the second link to slide longitudinally relative to the stationary housing and change the steering column position relative to the stationary housing.